Production of hydroxy fatty acids



Patented Jan.'9, 1945 PATENT OFFICE 2,357,050 monuc'rrou or nrnnoxy ram acms Donald Price, New York, N. Y., and Richard Griflith, Fairhaven, N. .L, assignors to National Oil Products Company, Harrison, N. 3., a corporation of New Jersey No Drawing. Application October 22, 1942,

SerlalNo. 462,908 1 16 Claims.

This invention relates in general to hydroxy fatty acids. more particularly to an improved process for the production of'hydroxy fatty acids from unsaturated fats and oils.

It is well known in the art that sulfated fatty materials may be readily produced by treating unsaturated oils and fatty acids with a sulfating agent such as sulfuric acid or oleum. The reaction isprincipally one of saturation of the double bonds by the addition thereto of a hydrogen ion and the H304 radical. After suifating, the ture is usually washed to remove most of the unspent sulfuric acid and the resulting mass neutralized. In the washing process a certain amount of the sulfuric acid ester group may be hydrolyzed with thesubstitution of a hydroxyl group in place thereof. If the sulfated fatty material is heated with a dilute or medium strength mineral acid, all of the H804 radicals may be split oif from the fatty material; and, theoretically, in each. case the H804 would be replaced by an OI-I group, thus producing a high yield ofhydroxy fatty acids. However, it is well known that such is not the case, and that in most instances, such an acid hydrolysis of sulfated fatty material will seldom yield more than about 25% to 30% of hydroxy fatty acids basedon the total of the fatty material actually sulfated. The yield is much lower when calculated on the total fatty material because, as is well known, most sulfated fatty materials seldom contain much more than about 50% of the theoretical content of organically combined sulfur. Consequently, it is not possible by means of such methods to obtain eflicient yields of hydroxy fatty acids.

It is the object of this invention to provide an improved process for the production of hy-' droxy fatty acids.

A further object of the invention is to produce hydroxy fatty acids from unsaturated fatty materials in greater yields and at a lower cost than hitherto possible.

We have found that hydroxy fatty acids may be readily and economically produced in very high yields from unsaturated fatty materials by subjecting such fatty materials to the action of a sulfating agent, hydrolyzing the sulfated material witlidilute mineral acid, and 'subwquently' subjecting the acid-hydrolyzed material toan 50 alkaline hydrolysis. Hydroxy fatty acids are readily recovered from the alkaline-hydrolyzed mass by acidification, which effects a splitting of the soaps formed during the alkaline hydrolysis, followed by recrystallization of the liberated hydroxy fatty acids from a suitable solvent, thus separating the hydroxy acids from any residual fatty material not converted to hydroxy acids.

It is not definitely known Just why our process 5 does produce a higher yield of hydroxy fatty acids than a mere acid hydrolysis, but the theory which we advance herewith may possibly be the explanation. However, since there may be other reasons why we obtain such high yields, we do 1'0;not confine ourselves to any particular theory "as to how our invention operates.

In acid hydrolysis of sulfated fatty material, a certain amount of hydroxy fatty acids are formed as has been mentioned hereinabove. Furthermore, a certain amount of hydroxy fatty acids maybe formed during the sulfation process, e. g., as a result of local overheating which, in the acid solution, will tend to hydrolyze the sulfate esters which have been formed. It is well known that carboxyl groups and hydroxyl groups will react with each other to form ester linkages. It is our belief that during the sulfation process, and possibly to some extent during the acid hydrolysis of the sulfated material, part of the hydroxygroups formed. react with carboxyl groups of other fatty acids to form esters, and in some cases it may be that several hydroxy fatty acids react with each other to form rather complex molecules. In fact, we have found that the residue remaining after removal of the hydroxy fatty acids from the a'cid-hydrolyzedmass contains compounds having molecular weights approximately four times as great as the molecular weight of the hydroxy fatty acids,'thus indicating that as many as four hydroxy fatty acids may be combined by means of ester linkages to form one large complex molecule, i. e., an estolide as, for example: i

H o=t:-(cm).- t-R I H Apparently these estolides are not readily broken down by acid hydrolysis, andconsequently part of the hydroxy acids which were formed by splitting oil the H504 radical are tied up in large so complex molecules. 'I'hesubsequent alkaline hymaterial.

drolysis, it is believed, breaks these ester linkages, thus reforming the hydroxy fatty acids which may then readily be recovered from the saponified mass. However, as aforementioned, we do not confine ourselves to this particular theory of how our invention operates, since there may be other reasons to explain its successful operation. y

In carrying out the process of the invention, any unsaturated fatty material, i. e., unsaturated fatty acids, fats, oils, or waxes containing esterified. fatty acids, may be employed as the starting Suitable fatty materials include, inter alia, oleic acid, palmitoleic acid, erucic acid, linoleic acid, ricinoleic acid, tall oil fatty acids 7 and other unsaturated fatty acids, soybean oil,

peanut oil,'rice bran oil, mustard seed oil, castor oil, teaseed oil, rapeseed oil, parsley seed oil, cod oil, menhaden oil and other fish oils containing esterified unsaturated fatty acids and other unsaturated fatty materials.

The unsaturated fatty material may be sulfated in any usual manner, although methods which vwill produce a relatively high content of organically bound sulfur are preferred, since the use thereof will aid in increasing the yield of the hydroxy fatty acids. After the fatty material has been sulfated, most of the unspent acid may be removed and the sulfated material then acidhydrolyzed with the free sulfuric acidremaining in the mixture by passing steam through the mixture, or by adding water and boiling the mass, or by the use of fat-splitting agents such as Twitchells reagent, various sulfonated aromatic compounds, etc. which will not only hydrolyze the glycerides but also split the sulfate esters, or by other suitable means. If desired, mineral acids other than sulfuric, e. g. hydrochloric acid, may be employed in the acid hydrolysis step. Sulfated oils, which have been prepared for other purposes, and in which all or practically all of the free acidity has been neutralized, may be used as the starting material. However, in most cases, it is of course preferable to start with the original unsuliated material, since certain steps which are necessary in the production of sulfated oils to be utilized for other purposes are not necessary in the preparation of the sulfated material prepared primarily for the production of hydroxy fatty acids.

After completion of the acid hydrolysis, the liberated hydroxy fatty acids may be separated from the reaction mass before proceeding with the alkaline hydrolysis step, if desired. However, it is not necessary to do so, and it is preferred not to do so since an extra step in the process is thus required. In carrying out the alkaline hydrolysis step, any suitable alkaline hydrolyzing process may be utilized. However, we prefer to admix the acid-hydrolyzed fatty material in an organic hydroxy solvent containing alkali, e. g. alcoholic alkali, and to carry out the-hydrolysis therein at an elevated temperature and in some cases at an elevated pressure. Suitable temperatures range from about 80 C. to 250 C., and suitable pressures are from one atmosphere to ten atmospheres or higher. This step of the process may conveniently be carried out in an autoclave.

Any suitable alkaline agent, e. g. sodium hydroxide or potassium hydroxide, may be employed. An amount thereof substantially in excess of the amount theoretically required to neutralize the carboxyl groups of the fatty acids and to insure complete hydrolysis of the estolides is preferably used. The hydroxy solvent utilized may be any which is suitable for carrying out an alkaline hydrolysis therein. However, we prefer to employ a hydroxylated fatty acid solvent such .as methanol, ethanol, isopropanol, glycerine, ethylene glycol, diethylene glycol, other glycol ethers, etc.

Uponcompletion of the alkaline hydrolysis, the

sulting solution to a temperature substantially below room temperature, e. g. 0 C. or below. At such low temperatures practically all of the hydroxy fatty acids will crystallize out and may be Y readily separated from the solution by means of filtration, centrifugation, or other suitable means. The hydroxy fatty acids may then be purified by means of recrystallization from a suitable solvent in much the same manner as they were separated from the reaction mass. In separating and purifying the hydroxy fatty acids by recrystallization from a fat solvent, it is preferred to employ aromatic or aliphatic hydrocarbon solvents and their halogenated derivatives such as heptane, octane, nonane, petroleum ether, cyclohexane, benzene, naphtha ethylene dichloride, trichlorethylene, etc., since hydroxy fatty acids are relatively immiscible with such solvents at room or lower temperatures. However, in certain cases the same solvent as was used in the alkaline hydrolysis step, i. e., propanol or isopropanol, may be employed in the separation and purification steps.

The fatty material which has not been converted to hydroxy fatty acids may be recovered from the solvent solution thereof in both the separation and purification steps of the process, and resulfated and rehydrolyzed whereby the total yield of hydroxy fatty acids is thus still further increased.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following examples which are given merely to further illustrate the invention and are not to be construed in a limiting sense, all parts given being by weight:

Example I 260 parts of sulfated oleic acid containing about 40% H20 and about 15% S03 were boiled for two hours with 163 parts of concentrated hydrochloric acid in 1450 parts of water. The aqueous-layer was removed and th oil heated for '7 hours at a temperature of about C. to C. at a pressure of about lbs./sq. in. with 250 parts of ethyl'alcohol and 120 parts of 50% aqueous NaOH. The saponified mass was acidified with hydrochloric acid, and solid hydroxy stearic acids were then recovered from the acidified mass and purified by recrystallization from Amsco Special Textile Spirit, a hydrocarbon solvent comprising chiefly octane. 73 parts of a mixture of Q-hydroxy and IO-hydroxy stearic acids were obtained. On the basis of the amount of fatty material that was actually sulfated, this represented approximately an 80% yield.

Example 11 used in Example I were refluxed with 163 parts of a sulfated. material selected from the group con.-

concentrated hydrochloric acid and 1000 of water for two hours as before. The oil layer was removed, dissolved in 310 parts of ethylene glycol containing 60 parts of sodium hydroxide and the solution refluxed at atmospheric pressure at a temperature of about 180 C. for hours.

Example I I I 1800 parts-of a sulfated castor oil containing about 9% of S0: and about 30% of water were heated with 1000 parts of water and 200 parts of concentrated hydrochloric acid as in the previous examples. The oil layer was then dissolved in 2000 parts of ethanol-and 1000 parts of a 50% aqueous sodium hydroxide solution added and the mass heated in much the same manner as in Example I. Acidification of the mass and recrystallization of the fatty material from Amsco Special Textil Spirit" as in Example I gave an excellent yield of dihydroxy stearlc acids.

Example IV duction of hydroxy fatty acids from unsaturated fatty materials.

Since certain changes may be made in carrying out the above'process without departing from the scope of theinvention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a, limiting sense. j

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In a process for the production of hydroxy fatty acids, -the steps which comprise subjecting a sulfated material selected from the group consisting of sulfated fatty acids, sulfated fatty oils, sulfated fats and sulfated fatty waxes to an acid hydrolysis and subjecting the acid-hydrolyzed mass to alkaline hydrolysis at a temperature within the range of 80 C. to 250C.

2. In aprocess for the production of hydroxy fatty acids, the steps which comprise subjecting a sulfated material selected from the group consisting of sulfated fatty acids, sulfated fatty oils, sulfated fats and sulfated fatty waxes to an acid hydrolysis and subjecting the acid-hydrolyzed mass to alkaline hydrolysis under elevated pressure at a temperature within the range of 80 C.

organic hydroxy solvent under elevated pressure at a temperature within the range 250 C.

4. In a process for the production of hydroxyfatty acids, the steps which comprise subjecting of 80 C. to

sisting of sulfated fatty acids, sulfa ted fatty oils, sulfated fats and sulfated fatty waxes to an acid hydrolysis and subjecting the acid-hydrolyzed mass to alkaline hydrolysis in the presence of ethanol under elevated pressure at a temperature within the range of 80 C. to 250 C.

. 5. In a process for the production of hydroxy fatty acids, the steps which comprise subjecting a sulfated material selected from the group consisting of sulfated fatty acids, sulfated fatty oils, sulfated fats and sulfated fatty waxes to an acid hydrolysis and subjecting the acid-hydrolyzed mass to alkaline hydrolysis in the presence of isopropanol under elevated pressure at a temperature within the range of 80 C. to 250 C.

6. In a process for the production of hydroxy fatty acids, the steps which comprise subjecting a. sulfated material selected from the group consisting of sulfated fatty acids, sulfated fatty oils, sulfated fats and sulfated fatty waxes to an acid hydrolysis and subjecting the acid-hydrolyzed mass to alkaline hydrolysis in the presence of ethylene glycol at a temperature within the range of 80 C. to 250 C.

7. A process for the production of hydroxy fatty acids, which comprises sulfating a fatty material selected from the group consisting of fatty acids, fatty oils, fats and fatty waxes, removing a. major portion of the unspent sulfuric acid, strongly heating the sulfated material' in the presence of water, subjecting the acid-hydrolyzed mass to alkaline hydrolysis at a temperature within the range of 80 C. to 250 C., splitting the hydroxy fatty acid soaps thus formed with acid and separating the hydroxy acids from the acidified mass.

8. A process for the production of hydroxy fatty acids, which comprises sulfating a fatty material selected from the group consisting of fatty acids, fatty oils, fats and fatty waxes, removing a major I portion of the unspent sulfuric acid, strongly heating the sulfated material in the presence of water, subjecting the acid-hydrolyzed mass to alkaline hydrolysis under elevated prmsure at a temperature within the range of 80 C. to 250 C., splitting the hydroxy fatty acid soaps thus formed with acid and separating the hydroxy acids from the acidified mass.

- 9. A process, for the production of hydroxy fatty acids, which comprises sulfating a fatty material selected from the group consisting of fatty acids, fatty oils, fats and fattywaxes, removing a major portion of the unspent sulfuric acid, strongly heating the sulfated material in the presence of water, subjecting the'acid-hydrolyzed mass to alkaline hydrolysis in the presence of an organic hydroxy solvent under elevated pressure at a temperature within the range of 80 C. to 250. C., splitting the hydroxy fatty acid soaps thus formed with acid and separating the hydroxy acids from the acidified mass.

10. A process for the production of hydroxy stearic acid, which comprises sulfating oleic acid, removing a major portion of the unspent sulfuric acid, strongly heating the sulfated ma terial in the presence of water, subjecting the acid-hydrolyzed mass to alkaline hydrolysis in the presence of an organic hydroxy solvent under elevated pressure at a temperature within the range of 80 C. to 250 C., splitting the hydroxy stearic acid soaps thus formed with acid and separating the hydroxy stearic acid from the acidified mass.

11.- A process for the production of dihydroxy stearic acid, which comprises aulfating ricinoleic acid, removing a major portion of the unspent sulfuric acid, strongly heating the auliated maelevated pressure at a temperature within the.

range of 80 C. to 250 C., splitting the dihydroxy stearic acid soaps thus formed. with acid and.

separating the dihydroxy stearic acid from the acidified mass.

12. A process for the production of dihydroxy stearic acid, which comprises sulfating castor oil, removing a major portion of the unspent sulfuric acid, strongly heating the sulfated material in the presence of water, subjecting theacid-hydrolyzed mass to alkaline hydrolysis in'the pres ence of an organic hydroxy solvent u'nderielevated pressure at a temperature within the range of 80 C. to 250 C., splitting the 'dihydroxy stearic acid soaps thus formed with acid and separating the dihydroxy stearic acid from the acidified mass,

13. A process for the production of hydroxy stearic acid, which comprises sultating oleic acid. removing amajor portion or the unspent sulfuric acid, strongly heating the sulfated material in the presence of water, subjecting the acid-hydrolyzed mass to alkaline hydrolysis in the presence of ethanol under elevated pressure at a. temperature within the range of 80 C. to 250 C., splitting the hydroxy stearic acid soaps thus formed with acid and separating the hydroxy stearic acid from the acidified mass.

14. A process for the production of hydroxy stearic acid, which comprises sulfating oleic acid,

aae'noco removing a major portion of the unspent sulfuric acid, strongly heating the sulfated material in the presence of water; subjecting the acid-hydrolyzed mass-to alkaline hydrolysis in the presence'of isopropanol under elevated pressure at a temperature within the range of 80 C. to 250 C.,

splitting the hydroxy stearic acid soaps thus formed with acid and separating the hydroxy stearic acid from the acidified mass.

15. A process for the production of .hydroxy stearic acid, which comprises suliating oleic acid, removing a major portion of the unspent sulfuric acid, strongly heating the sulfated material in the presence of water, subjecting the acidhydrolyzed mass to alkaline hydrolysis in the presence of ethylene glycol at a temperature within the range of 80 C. to 250 C., splitting the hydroxy stearic acid soaps thus formed with acid and separating the hydroxy stearic acid from the acidified mass.

16. A process for the production of hydroxy stearic acid, which comprises sulfating oleic acid, removing a major portion of the unspent sulfuric acid, strongly heating the sulfated material in the presence of water, subjecting the acidhydrolyzed mass to alkaline hydrolysis in the presence of an organic hydroxy solvent under elevated pressure at a temperature within the range of 80 C. to 250 C., splitting the hydroxy stearic acid soaps thus formed with acid, dissolving. the mass in a non-polar fat solvent and recovering the hydroxy stearic acid by crystallization thereof from the fat solvent.

DONALD PRICE. RICHARD GRIFFITH. 

